Conference call and mobile communication devices that participate in a conference call

ABSTRACT

A mobile communication device that comprises a microphone, a speaker, an input output port and one or more modules; wherein the microphone is configured to receive, during a conference call, (a) an acoustic signal from a first person, and (b) a cross echo from a speaker of another mobile communication device that participates in the conference call, the cross echo is generated as a result of the acoustic signal from the first person; and wherein the one or more modules are configured to cancel the cross echo based, at least in part, of the acoustic signal of the first person.

CROSS REFERENCE

This application claims priority from U.S. provisional patent Ser. No.62/306,101 filing date Mar. 10, 2016.

BACKGROUND

There is a growing need to allow people to conduct conference calls in acost-effective manner.

SUMMARY

Methods, systems, and mobile communication devices as illustrated in thespecification and/or the claims.

There may be provided a mobile communication device that may include amicrophone, a speaker, an input output port and one or more modules;wherein the microphone may be configured to receive, during a conferencecall, (a) an acoustic signal from a first person, and (b) a cross echofrom a speaker of another mobile communication device that participatesin the conference call, the cross echo may be generated as a result ofthe acoustic signal from the first person; and wherein the one or moremodules may be configured to cancel the cross echo based, at least inpart, of the acoustic signal of the first person.

The input output port may be configured to receive a digital leakagesignal; wherein the one or more modules may be configured to cancel thedigital leakage signal based, at least in part, on the acoustic signalof the first person; and wherein the digital leakage signal may resultfrom the acoustic signal from the first person and may be an output of afeedback path that may include the mobile communication device, theother mobile communication device and a mixer.

The microphone may be configured to receive an echo from the speaker,wherein the echo resulted from the digital leakage signal; and whereinthe one or more modules may be configured to cancel the echo from thespeaker based, at least in part, of the acoustic signal of the firstperson.

The digital leakage signal may result from a reception, by a mixer, of adigital output signal from the other mobile communication device;wherein the digital output signal may be generated by the other mobilecommunication device in response to the acoustic signal from the firstperson.

The microphone may be configured to receive an echo from the speaker;and wherein the echo resulted from the acoustic signal from the firstperson and may be an output of a feedback path that may include themobile communication device, the other mobile communication device and amixer.

The input output port may be configured to receive, from a furthermobile communication device, a digital signal that may be related toacoustic signal generated by a further person.

The one or more modules may be configured to compensate for differencesbetween delays associated with (a) a reception of traffic from thefurther mobile communication device by the mobile communication deviceand (b) a reception of traffic from the further mobile communicationdevice by the other mobile communication device.

The one or more modules may be configured to change a signal may beprovided to the speaker.

There may be provided a mobile communication device that may include amicrophone, a speaker, an input output port and one or more modules;wherein the microphone may be configured to receive, during a conferencecall, (a) an acoustic signal from a first person, and (b) an echo from aspeaker of the mobile communication device, the echo may be generated asa result of a digital leakage signal from another mobile communicationdevice that participates in the conference call, the digital leakagesignal may result from the acoustic signal of the first person; whereinthe one or more modules may be configured to cancel the echo based, atleast in part, of the acoustic signal of the first person.

The one or more circuits may be configured to change a signal that maybe fed to the speaker.

The one or more circuits may be configured to cancel a signal that maybe fed to the speaker.

There may be provided a method for participating in a conference call,the method may be executed by a mobile communication device that mayinclude a microphone, a speaker, an input output port and one or moremodules, wherein the method may include: receiving, by the microphone,during the conference call, (a) an acoustic signal from a first person,and (b) a cross echo from a speaker of another mobile communicationdevice that participates in the conference call, the cross echo may begenerated as a result of the acoustic signal from the first person; andcancelling, by the one or more modules, the cross echo based, at leastin part, of the acoustic signal of the first person.

The method may include receiving by the input output port a digitalleakage signal; cancelling, by the one or more modules, the digitalleakage signal based, at least in part, of the acoustic signal of thefirst person; and

wherein the digital leakage signal may result from the acoustic signalfrom the first person and may be an output of a feedback path that mayinclude the mobile communication device, the other mobile communicationdevice and a mixer.

The method may include receiving, by the microphone, an echo from thespeaker, wherein the echo resulted from the digital leakage signal; andcancelling, by the one or more modules, the echo from the speaker based,at least in part, of the acoustic signal of the first person.

The digital leakage signal may result from a reception, by a mixer, of adigital output signal from the other mobile communication device;wherein the digital output signal may be generated by the other mobilecommunication device in response to the acoustic signal from the firstperson.

The method may include receiving, by the microphone, an echo from thespeaker, and wherein the echo resulted from the acoustic signal from thefirst person and may be an output of a feedback path that may includethe mobile communication device, the other mobile communication deviceand a mixer.

The method may include receiving, by the input output port, from afurther mobile communication device, a digital signal that may berelated to acoustic signal generated by a further person.

The method may include compensating, by the one or more modules, fordifferences between delays associated with (a) a reception of trafficfrom the further mobile communication device by the mobile communicationdevice and (b) a reception of traffic from the further mobilecommunication device by the other mobile communication device.

The method may include changing, by the one or more modules a signal maybe provided to the speaker.

There may be provided a method for participating in a conference call,the method may be executed by a mobile communication device that mayinclude a microphone, a speaker, an input output port and one or moremodules, wherein the method may include receiving, by the microphone,during a conference call, (a) an acoustic signal from a first person,and (b) an echo from a speaker of the mobile communication device, theecho may be generated as a result of a digital leakage signal fromanother mobile communication device that participates in the conferencecall, the digital leakage signal may result from the acoustic signal ofthe first person; and cancelling, by the one or more modules, the echobased, at least in part, on the acoustic signal of the first person.

The method may include changing, by the one or more modules a signal maybe provided to the speaker.

The method may include cancelling, by the one or more modules a signalmay be provided to the speaker.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be appreciated that for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn to scale.For example, the dimensions of some of the elements may be exaggeratedrelative to other elements for clarity. Further, where consideredappropriate, reference numerals may be repeated among the figures toindicate corresponding or analogous elements.

FIG. 1A illustrates three persons that participate in a conference call,a mixer and three devices according to an embodiment of the invention;

FIG. 1B illustrates three persons that participate in a conference call,a network and three devices according to an embodiment of the invention;

FIG. 1C illustrates three persons that participate in a conference call,a connecting network, a near-end network and three devices according toan embodiment of the invention;

FIG. 2A illustrates a third person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 2B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 2A according to an embodiment of the invention;

FIG. 3A illustrates a first person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 3B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 3A according to an embodiment of the invention;

FIG. 4A illustrates a third person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 4B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 4A according to an embodiment of the invention;

FIG. 5A illustrates a third person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 5B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 5A according to an embodiment of the invention;

FIG. 6A illustrates a first person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 6B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 6A according to an embodiment of the invention;

FIG. 7A illustrates a first person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 7B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 7A according to an embodiment of the invention;

FIG. 7C illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 7A according to an embodiment of the invention;

FIG. 8A illustrates a first person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention;

FIG. 8B illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 8A according to an embodiment of the invention;

FIG. 8C illustrates various components and one or more compensationmodules for performing compensation operations related to some of thesignals of FIG. 8A according to an embodiment of the invention;

FIG. 9A illustrates various components and one or more compensationmodules of a first device of a first person according to an embodimentof the invention;

FIG. 9B illustrates various components and one or more compensationmodules of a first device of a first person according to an embodimentof the invention;

FIG. 9C illustrates various components and one or more compensationmodules of a first device of a first person according to an embodimentof the invention;

FIG. 9D illustrates various components and one or more compensationmodules of a first device of a first person according to an embodimentof the invention;

FIG. 10A illustrates a third person that talks during conference call, anear end network, a connecting network, three devices and varioussignals generated during the conference call according to an embodimentof the invention;

FIG. 10B illustrates a person that talks during conference call, a nearend network, a connecting network, three devices and various signalsgenerated during the conference call according to an embodiment of theinvention;

FIG. 11A illustrates a third person and a first person that talk duringconference call, a mixer, three devices that include a second devicethat has a turned off microphone, and various signals generated duringthe conference call according to an embodiment of the invention;

FIG. 11B illustrates a third person and a first person that talk duringconference call, a mixer, three devices that include a second devicethat has a turned off speaker, and various signals generated during theconference call according to an embodiment of the invention;

FIG. 11C illustrates a third person and a first person that talk duringconference call, a mixer, three devices that include a second devicethat has a turned off microphone and a first device with a turned offspeaker, and various signals generated during the conference callaccording to an embodiment of the invention;

FIG. 11D illustrates a third person and a first person that talk duringconference call, a mixer, three devices that include a second devicethat has a turned off microphone, a third device with a turned offmicrophone, and a first device with a turned off speaker, as well asvarious signals generated during the conference call according to anembodiment of the invention; and

FIG. 12A illustrates a second person that talks during conference call,a mixer, three devices, and various signals generated during theconference call according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, and components have notbeen described in detail so as not to obscure the present invention.

The term “comprising” is synonymous with (means the same thing as)“including,” “containing” or “having” and is inclusive or open-ended anddoes not exclude additional, unrecited elements or method steps.

The term “consisting” is a closed (only includes exactly what is stated)and excludes any additional, unrecited elements or method steps.

The term “consisting essentially of” limits the scope to specifiedmaterials or steps and those that do not materially affect the basic andnovel characteristics.

In the claims and specification any reference to the term “comprising”(or “including” or “containing”) should be applied mutatis mutandis tothe term “consisting” and should be applied mutatis mutandis to thephrase “consisting essentially of”.

In the claims and specification any reference to the term “consisting”should be applied mutatis mutandis to the term “comprising” and shouldbe applied mutatis mutandis to the phrase “consisting essentially of”.

In the claims and specification any reference to the phrase “consistingessentially of” should be applied mutatis mutandis to theterm“comprising” and should be applied mutatis mutandis to the term“consisting”.

Any reference in the specification to a method should be applied mutatismutandis to a system capable of executing the method.

Any reference in the specification to a system should be applied mutatismutandis to a method that may be executed by the system.

The terms “cancellation”, “suppression” are used in an interchangeablemanner.

The term “substantially” or “about” can refer to an accuracy (ordeviation) of any value between 1 and 20 percent.

The term “proximate” may refer to a range of distances that may span,for example, between a fraction of a millimeter and less than 5centimeters.

Any combination of any components of any of the devices and/or systemsillustrated in any of the figures may be provided.

Any device, network, mixer, module and/or system that is illustrated inany of the figures may include additional components, may includealternative components, may include fewer components, may be limited tothe components illustrated in the figure or may be essentially limitedto the components illustrated in the figure.

There is provide a method for conducting conference calls using mobiledevices and an additional mixer and/or network that may convey signalsbetween the mobile device.

The mobile device may be a smartphone. Baby monitor, mobile devices usedby public security officers, mobile gaming consoles, but any othermobile device that includes a speaker, a microphone and compensationmodules (as illustrated below) can be used for conducting conferencecalls.

In various figures three persons participate in the conference call,wherein the first and second persons are at the same space/can be heardby each other. This is only for brevity of explanation. The number ofparticipants in a conference call may exceed three. The participants maybe arranged in other manners. For example—more than three participantsmay be located in the same room and more than a single participant maybe located at another room.

Some of the various figures illustrates a single talking participant andother figures illustrated two persons that talk. It is noted that anycombination of participants may talk at the same time.

In the various figures the first and second persons 11 and 12 arelocated at the same room and may be referred to as near endparticipants. The third person is located at another room and isreferred to as a far end participant.

It should be noted that the persons may be located at any location—in orout a room.

The following signals illustrate various signals. The signals were namedby names that may refer to (a) the person that either generated thesignal or resulted in the generation of the signal, (b) the device thateither received the signal or generated the signal, (c) a type of thesignal—acoustic, digital, leakage or converted signal.

A converted signal may be outputted from a microphone and represents anacoustic signal received by the microphone. The converted signal mayhave also been processed by one or more modules such as signalprocessing modules including but not limited to filters and the like.

TABLE 1 lists some of the signals that are illustrated in the drawings:

TABLE 1 # Name remark 1011 First user first Acoustic signal generated bythe first user and microphone acoustic received by the first microphonesignal 1012 First user second Acoustic signal generated by the firstuser and microphone acoustic received by the second microphone signal1013 First user second Acoustic signal generated by the first microphoneas device acoustic a result from a digital leakage signal from thesecond leakage signal device through the mixer and to the first device,in response to the acoustic signal generated by the first user 1014First user first device Acoustic signal generated by the secondmicrophone acoustic leakage as a result from a digital leakage signalfrom the first signal device through the mixer and to the second device,in response to the acoustic signal generated by the first user 1031Third user first Acoustic signal generated by the first speaker inspeaker acoustic response to the acoustic signal generated by the thirdsignal user 1032 Third user second Acoustic signal generated by thesecond speaker in speaker acoustic response to the acoustic signalgenerated by the third signal user 1041 Third user first Echo of thefirst device (from speaker to microphone) device echo in response to theacoustic signal generated by the third user 1041′ Converted third userSignal 1041 after conversion to an electrical signal by first deviceecho first microphone 1042 Third user second Echo of the second device(from speaker to device echo microphone) in response to the acousticsignal generated by the third user 1043 First user first device Echo ofthe first device (from speaker to microphone) echo in response to adigital leakage signal from the second device through the mixer and tothe first device, leakage resulting from response to the acoustic signalgenerated by the first user 1044 First user second Echo of the seconddevice (from speaker to device echo microphone) in response to a digitalleakage signal from the first device through the mixer and to the seconddevice, leakage resulting from response to the acoustic signal generatedby the first user 1051 Third user first cross Cross echo (from secondspeaker to first microphone) echo in response to the acoustic signalgenerated by the third user 1052 Third user second Cross echo (fromfirst speaker to second microphone) cross echo in response to theacoustic signal generated by the third user 1052′ Converted third userSignal 1052 after conversion to an electrical signal by second echosignal first microphone 1053 First user first device Echo from the firstdevice that is received by the cross echo second device and results fromdigital leakage from the second device via the mixer and to the firstdevice, the echo results from the acoustic signal generated by the firstuser 1054 First user second Echo from the second device that is receivedby the device cross echo first device and results from digital leakagefrom the first device via the mixer and to the second device, the echoresults from the acoustic signal generated by the first user 1111 Firstuser first device Digital signal outputted by the first device indigital signal response to the acoustic signal generated by the firstuser. 1112 First user second Digital signal outputted by the seconddevice in device digital signal response to the acoustic signalgenerated by the first user 1131 Third user first Digital signaloutputted by the mixer and received by device input signal the firstdevice in response to the acoustic signal generated by the third user1131′ Converted third user Signal 1131 after conversion to an electricalsignal by first device input first microphone signal 1132 Third usersecond Digital signal outputted by the mixer and received by deviceinput signal the second device in response to the acoustic signalgenerated by the third user 1141 First user second Digital leakagesignal from the first device through digital leakage signal the mixerand to the second device, in response to the acoustic signal generatedby the first user 1142 First user first digital Digital leakage signalfrom the second device leakage signal through the mixer and to the firstdevice, in response to the acoustic signal generated by the first user1310 First user mixed Digital signal outputted by the mixer in responseto digital signal the acoustic signal generated by the first user 1330Third user third Digital signal outputted by the third device in devicedigital signal response to in response to the acoustic signal generatedby the third user 1335 Third user Digital signal outputted by theconnecting network in connecting network response to in response to theacoustic signal digital signal generated by the third user 1336 Firstuser first device Digital signal outputted by the first device to theconnecting network connecting network in response to the acoustic signaloutput signal generated by the third user 1337 First user connectingDigital signal outputted by the connecting network in network outputresponse to the acoustic signal generated by the third signal user 1410First user third Acoustic signal outputted by the third speaker indevice acoustic response to in response to the acoustic signal outputsignal generated by the first user 1430 Third user third Acoustic signalgenerated by the third user and microphone acoustic received by thethird microphone signal 1501 Third user first Digital signal outputtedby the first device to the near device near end end network in responseto the acoustic signal network digital generated by the third usersignal 1502 Third user near end Digital signal outputted by the near endnetwork to network second the second device in response to the acousticsignal device digital signal generated by the third user 1511 First usernear end Digital signal outputted by the near end network to networksecond the first device in response to the acoustic signal devicedigital signal generated by the first user 1512 First user secondDigital signal outputted by the second device to the device near endnear end network in response to the acoustic signal network digitalgenerated by the first user signal 1601 Second user first Acousticsignal generated by the second user and user acoustic signal received bythe first user (for example - without using any device) 1602 Second usersecond Acoustic signal generated by the second user and microphoneacoustic received by the second microphone signal 1603 Second usersecond Digital signal outputted by the second device in device digitalsignal response to the acoustic signal generated by the second user 1604Second user first Acoustic signal generated by the second user andmicrophone acoustic received by the first microphone signal 1605 Seconduser first Digital leakage signal from the second device digital leakagesignal through the mixer and to the first device, in response to theacoustic signal generated by the second user 1606 Second user firstDigital signal outputted by the first device in device digital signalresponse to the acoustic signal generated by the second user. 1607Second user mixed Digital signal outputted by the mixer in response todigital signal the acoustic signal generated by the second user 1608Second user third Acoustic signal outputted by the third speaker indevice acoustic response to in response to the acoustic signal outputsignal generated by the second user

FIG. 1A illustrates three persons 11, 12 and 13 that participate in aconference call, a mixer 25 and three devices—first device 21, seconddevice 22 and third device 23 that may (or may not) belong to first tillthird persons 11, 12 and 13 respectively.

First device 21 includes first microphone 41, first speaker 31 and firstinput output (I/O) port 51. Second device 22 includes second microphone42 and second speaker 32 and second I/O port 52. Third device 23includes third microphone 43 and third speaker 33 and third I/O port 53.

An input output (I/O) port may be any communication port—especially notan acoustic port. The I/O port may be, for example a wireless or wiredcommunication port. The I/O port may be used for outputting digitalsignals and/or representations of digital signals. The/O port may beused to convey radio frequency (RF) signals and/or other signals.

FIG. 1A also illustrates the acoustic link 80 between first and secondpersons 11 and 12—as these persons may hear each other without usingdevices.

There may be delays between the transmission and/or reception of signalsbetween the mixer and each one of the first and second devices.

A difference between network delays from the mixer to the first andsecond device is denoted reception delay difference (Drx).

A difference between network delays from the first and second devices tothe mixer is denoted transmitted delay difference (Drx).

FIG. 1A illustrates first Rx delay 91, second Rx delay 92, first Txdelay 93, and second Tx delay 94.

FIG. 1A further illustrates first room 81 in which first and secondpersons, first and second device and mixer are located as well as secondroom 82 in which third person and third device are located.

The mixer may be located elsewhere, and may be replaced by one or morenetworks.

FIG. 1B illustrates three persons 11, 12 and 13 that participate in aconference call, a network 26 and three devices according to anembodiment of the invention. Network of FIG. 1B replaces mixer 25 andhas mixing capabilities for combining the signals from first and seconddevices.

FIG. 1C illustrates three persons 11, 12 and 13 that participate in aconference call, a connecting network 28, a near-end network 27 andthree devices 21, 22 and 23 according to an embodiment of the invention.

In FIG. 1C the connecting network 28 (may be a long-range network suchas the Internet or any long-range network) communicates with the firstdevice and may not communicate with the second device. The near-endnetwork 27 may relay signals (for example digital signals) between firstand second devices.

Near-end network may be a short-range network such as but not limited toBluetooth, BLE, WI-FI, PROSE Relay from PSLTE, voice over IP etc.

FIG. 2A illustrates a third person 13 that talks during conference call,a mixer 25, three devices 21, 22 and 23 and various signals 1430, 1330,1131, 1132, 1031 and 1032 generated during the conference call accordingto an embodiment of the invention.

As indicated above there may be a delay difference of Drx betweensignals 1131 and 1132. Unless compensated signals 1031 and 1032 maysuffer from a delay difference of Drx.

The perceived speech quality and intelligibility decreases due to Drx.

Drx should be estimated and compensated in each near-end device or atleast in one of the first and second devices

Drx may be estimated in various manners. For example—Drx may beestimated by cross correlation between signals 1031 and 1032 which arereceived by the microphones of both devices as echo. Additionally oralternatively, the correlation between 1031 and 1131 in the first devicecan be used to estimate the delay.

In circuit switched networks, this delay can be constant. In packetswitched network (e.g. VOIP, VOLTE) the delay can be time variant andestimated continuously

Estimation module can get info from jitter buffer module that managesdynamic delays to avoid packet losses.

The jitter buffer mentioned above may be in the communication processor,in the Rx path, as an interface between the network. It is used tosynchronized the order of received packets from the networks. The jitterbuffer may be used to apply dynamic buffering to get rid of networkdelay variations.

Each one of the mentioned above or below AEC modules may operate on thedigitally sampled audio signals of the communication device. Thetransfer function of the acoustic environment from the loudspeaker tothe microphone on the device is estimated to cancel the received echoesfrom the microphone signal. The AEC may be or may include an adaptivefilter. An adaptive filter is used in voice echo cancellation toaccommodate the time varying nature of the echo path. The filter learnsthe path when the far-end speaker is talking and the near-end speaker issilent and adjusts its coefficients (transfer function) according to thealgorithm optimization criterion.

Any AFC module may apply Non-Linear Processing. Non-linear processing isthe removal of residual echo left by the adaptive filter (echocancellation). Residual echoes are the un-modeled components of the echopath. Most adaptive filters are linear and can only cancel the linearportions of the echo path. Thus the nonlinear portions cannot be removedvia the adaptive filter and a residual echo suppressor follows thefilter to handle nonlinear portions of the echo that remain.

FIG. 2B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (such as delayunit Drx 62 and Drx estimation module 61) for performing compensationoperations related to signals of FIG. 2A according to an embodiment ofthe invention.

Drx estimation module 61 may estimate Drx using, for example correlationbetween converted third user second cross echo 1052′ and converted thirduser first device echo 1041′.

Additionally or alternatively, the correlation between 1031 and 1131 inthe first device can be used to estimate the delay.

Delay unit Drx 62 may delay converted third user first device echo 1041′before it is fed to first speaker in order to generate a third userfirst speaker acoustic signal 1031 that is Drx compensated.

The Drx compensation may be performed by the first device, by the seconddevice or by both first and second devices.

FIG. 3A illustrates a first person that talks during conference call, amixer, three devices and various signals 1011, 1012, 1111, 1112, 1310and 1410 generated during the conference call according to an embodimentof the invention.

There may be a delay difference of Dtx between signals 1111 and 1112.Without Dtx compensation the mixer 25 may mix time shifted signals andthe third person will eventually receive a mixture of time shiftedsignals. The perceived speech quality and intelligibility decreases dueto Dtx.

Dtx should be estimated and compensated in at least one of the first andsecond devices.

The first and second device may not be aware of Dtx but may estimate Dtxbased on Drx.

The third device may can apply de-reverberation techniques to solve theproblem.

The third device may estimate Dtx by analyzing signal 1310 and may sendfeedback to the first and second devices.

FIG. 3B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (such as delayunit Dtx 64 and Dtx estimation module 63) for performing compensationoperations related to signals of FIG. 3A according to an embodiment ofthe invention.

Dtx estimation module 63 may estimate Trx using, for example correlationbetween converted third user second cross echo 1052′ and converted thirduser first digital input signal 1131′.

Delay unit Trx 64 may delay a converted first user first microphoneacoustic signal (converted by microphone from first user firstmicrophone acoustic signal 1011) before it is fed to mixer in order togenerate a first user first device digital signal that is Trxcompensated.

The Trx compensation may be performed by the first device, by the seconddevice or by both first and second devices.

FIG. 4A illustrates a third person 13 that talks during conference call,a mixer 25, three devices 21, 22 and 23 and various signals 1430, 1330,1131, 1132 1041 and 1042 generated during the conference call accordingto an embodiment of the invention.

In a hand-free mode there may be an echo due to the acoustic couplingbetween the microphone and the speaker of each device.

FIG. 4B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (first echocancellation unit (AEC1) 65) for performing compensation operationsrelated to some of the signals of FIG. 4A according to an embodiment ofthe invention.

AEC1 65 may apply one or more linear and/or non-linear echo cancellationprocesses. Additionally or alternatively, AEC1 may apply linear and/ornon-linear echo suppression processes. Non-linear echo components mayresult from non-linearity of the speaker transfer function and/or fromvibrations of the device.

The third user first device echo 1041 is received by first microphoneand is converted to converted third user first device echo 1041′. Thethird user first device echo 1041 is generated by first speaker 31 inresponse to third user first device digital input signal 1131. AEC1performs echo cancellation after being fed by third user first devicedigital input signal 1131 and converted third user first device echo1041′. The output of AEC1 65 is sent from first I/O port 51 to mixer 25.

FIG. 5A illustrates a third person 13 that talks during conference call,a mixer 25, three devices 21, 22 and 23 and various signals 1430, 1330,1132, 1131, 1051 and 1052 generated during the conference call accordingto an embodiment of the invention.

A cross acoustic echo problem exists due to acoustic coupling betweenthe speaker or one device and a microphone of another device. This isespecially true when the first and second devices are expected to be atthe same room and relatively proximate to each other (for example—lessthan 10 meters)—as the first and second persons need to use thesedevices during the conference call and may also need to hear each otherwithout the aid of these devices.

The cross echo may be cancelled using at least one linear and/ornon-linear echo cancel processes and at least one linear and/ornon-linear echo suppression processes.

In addition, Drx should be compensated in the Rx path.

The non-linear cross echo is due to speaker non-linearity and non-lineardifferences due transmission links (between first and second device,mixer and third device) that may include vocoders and time-variantnetwork delays.

Direct echo cancellation (AEC₁) and cross echo cancellation (AEC₂) canbe done jointly using the same module when the delay is compensatedcorrectly.

For example, assuming signals 1131 and 1132 are the same but with delaydifference because of different network delays. First microphone 21 getsboth the echo of 1131 and an echo of 1132. AEC1 aims to cancel the1131-21 coupling while AEC2 aims to cancel 1132-21 coupling. Since 1131and 1132 are the same with different delays, we can use a joint AEC tocancel jointly 1131-21 and 113-21 coupling using 1131 as reference toAEC.

FIG. 5B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (such as secondecho cancellation unit (AEC2) 66, delay unit Drx 62 and Drx estimationmodule 61) for performing compensation operations related to some of thesignals of FIG. 5A according to an embodiment of the invention.

The first microphone 41 may sense third user second cross echo 1052 andoutput a converted third user second cross echo 1052′. The convertedthird user second cross echo 1052′ may be fed to AEC2.

FIG. 6A illustrates a first person that talks during conference call, amixer, three devices and various signals generated during the conferencecall according to an embodiment of the invention.

When the first person (or the second person) talks his speech (acousticsignal) is captured by first and second microphones of first and seconddevices (signals 1011 and 1012), causes digital signals 1111 and 1112 tobe outputted from first and second devices to be sent to mixer andcauses digital leakage signals 1141 and 1142 to reach second and firstdevices respectively. These digital leakage signals cause first andsecond speakers to output acoustic leakage signals 1013 and 1014.

The first and second persons perceives the acoustic leakage signals asunwanted delayed echo and can make the participation in the conferencecall impossible or non-tolerable.

The acoustic leakage signals may be cancelled by AEC3 using at least onelinear and/or non-linear echo cancel processes and at least one linearand/or non-linear echo suppression processes.

AEC3 is the same module with AEC1. (Use of AEC3 is the most innovativepart of the patent)

AEC3 may perform the echo cancellation and/or suppression using thecorrelation between the original speech (signals 1011 and 1012) and theoutput acoustic leakage signals 1013 and 1014.

AEC3 can be implemented a correlator as feedback detector and attenuatorwhenever feedback exists.

AEC3 may benefit from receiving an estimate of Dn. Dn may be estimatedusing cross correlation or any other method and need to be compensated.

Dn is the time for the transmission of: 1012-1112-1142 using the factthat 1011=1012. It is estimated by correlating converted version of 1011and 1142.

FIG. 6B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (Third echocancellation unit (AEC3) 67, Delay unit Dn 69 and Dn estimation module68) for performing compensation operations related to some of thesignals of FIG. 6A according to an embodiment of the invention.

The output of first microphone 41 is fed to delay unit Dn that sends adelayed signal (delayed by Dn) to AEC3 67. AEC3 also receives signal1111 and perform echo cancellation and/or echo suppression to provide anoutput signal to speaker.

Dn estimation module 68 may estimate Dn by correlating between signals1111 and 1142.

AEC2 may be the same as AEC1 and the same as AEC3. Regarding AEC3—AEC3manipulates the input signal to the speaker and can even mute thespeaker, because the first and second users may hear each other withoutthe assistance of their devices—and thus can improve the echocancellation in a substantial manner.

FIG. 7A illustrates a first person that talks during conference call, amixer, three devices and various signals 1011, 1012, 1111, 1112, 1141,1141, 1310 and 1410 that are generated during the conference callaccording to an embodiment of the invention.

When first person talks and if the feedback is not cancelled with AEC₃or there exists some residual feedback, an echo signal (such as signals1043 and 1044) from a speaker is received by the microphone of the samedevice. The content of the residual feedback depends on whether there isan AEC3 or not and if there—on the output of AEC3.

The echo may be cancelled and/or suppressed by first echo cancellationunit (AEC1) 65 that may apply one or more linear and/or non-linear echocancellation processes. Additionally or alternatively, AEC1 may applylinear and/or non-linear echo suppression processes.

It should be noted that successful implementation of AEC3 may avoid thegeneration of acoustic leakage signals 113 and 1014.

FIG. 7B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules for performingcompensation operations related to some of the signals of FIG. 7Aaccording to an embodiment of the invention.

The first user first device echo 1043 is received by first microphoneand is converted to a converted first user first device echo that is fedto AEC1 65. AEC1 also receives first user second device digital leakagesignal 1142.

When the first person talks signals 1031 and 1032 are received by themicrophones of the first and second devices.

Digital leakage signals 1141 and 1142 may be used by the AEC1 of thefirst and second devices as echo references.

If the digital leakage signals 1141 and 1142 are not cancelled with anyAEC3 then the desired signal (signals 1011 and 1012) may be suppressedby the AEC1 of the first and second devices due to the existence ofnon-zero value echo references-which are the digital leakage signals.

In AEC1, output of AEC3 which gets 1142 as input is used as referencesignal. So when AEC3 does not cancel the signal completely, AEC1 willtry to cancel the echo of the output of AEC3. On the other hand, thefirst person is still talking and generating 1011 as input to AEC1.

This generates a double talk situation which always exists when thefirst person is talking where AEC1 will do echo suppression and suppressthe desired signal of the first person.

AEC1 should apply a double talk detection which can also detect feedbacksituation in order not to clip the desired speech of the first person,

This unwanted suppression of signals 1011 and 1012 may result in areception, by the third person, of clipped and not intelligible speechsignal 1410.

While using AEC3 the feedback will be cancelled and feedback-free signalwill be used as reference to avoid clipping of the speech of the firstperson.

AEC1 may include additional control mechanism to avoid this clipping

FIG. 7C illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules for performingcompensation operations related to some of the signals of FIG. 7Aaccording to an embodiment of the invention.

The output of first microphone 41 is fed to AEC1 65. AEC1 65 is also fedwith the output of AEC3 67. AEC1 65 outputs first user first devicedigital device output signal 1111.

AEC3 67 receives the first user second device digital leakage signal1142 and receives (from delay unit Dn 69) a Dn-delayed first user firstdevice digital device output signal 1111.

Delay unit Dn receives the estimate of Dn from Dn estimation module 68.

FIG. 8A illustrates a first person that talks during conference call, amixer, three devices and various signals 1011, 1012, 1053, 1054, 1111,1112, 1141, 1142, 1310 and 1410 that are generated during the conferencecall according to an embodiment of the invention.

When the first person talks and if the feedback is not cancelled withAEC3 of the other device or there exists still some residual feedback,it is played to the speaker of one device out of the first and seconddevices and is received as a cross echo of a microphone of anotherdevice out of the first and second device. A first feedback pathincludes first microphone, first device to mixer, mixer to second deviceand second speaker—signals 1011, 1111, 1141 and 1054. A second feedbackpath includes second microphone, second device to mixer, mixer to firstdevice and first speaker—signals 1012, 1112, 1141 and 1053.

There feedback paths result in a howling effect.

A cross echo (out of 1053 and 1054) may exist if the AEC3 of the devicethat outputted that cross echo did not exist or did not cancel thefeedback completely.

Successful implementation of AEC3 in each of the first and seconddevices may avoid the generation of the cross echoes and thus avoidfeedback and howling.

The howling may be cancelled by using linear and/or non-linear acousticfeedback canceller.

Feedback path includes 1011-1111-1141-1054 and feedback cancellation isdone between 1011 and 1054—which is a delayed version of 1011.

Additionally or alternatively, the echo cancelling may be executed on1111 (that results from 1011) and delayed version of 1111 (tat resultsfrom 1054).

Non-linear feedback is due to speaker non-linearity, vocoder andtime-variant delay

The network delay need to be estimated using cross correlation or anyother method.

An alternative method is a special linear and non-linear echocancellation (AEC4) since the digital leakage signals 1142 and 1141 arecorrelated to the cross echoes 1053 and 1054.

FIG. 8B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (such as fourthecho cancellation unit (AEC4) 70) for performing compensation operationsrelated to some of the signals of FIG. 8A according to an embodiment ofthe invention.

AEC4 70 is fed by the converted signal from first microphone (aconverted first used second device cross echo) and by a first usersecond device digital leakage signal 1142 and perform echo cancellationand/or echo suppression to output first user first device digital outputsignal 1111.

FIG. 8C illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules (AFC 71, delayunit Dn 69) for performing compensation operations related to some ofthe signals of FIG. 8A according to an embodiment of the invention.

AFC 71 is fed by the converted signal from first microphone (a convertedfirst used second device cross echo) and by delayed (by Dn) first userfirst device digital output signal 1111.

FIG. 9A illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules AEC1 65, AEC2 66,AFC 71, AEC3 67, Delay unit Dn 69, Delay unit Dtx 64, Delay unit Drx 62,Dn estimation module 68, Dtx estimation module 63 and Drx estimationmodule 61 of first device 21 according to an embodiment of theinvention.

The input of delay unit Drx 62 is fed by first device input digitalsignals such as 1131. Delay unit Drx 62 performs Drx compensation. Theduration of Drx can be learnt by Drx estimation module 61 that iscoupled to Delay unit Drx 62.

The output of Delay unit Drx 62 is coupled to a first input of AEC3 67.AEC3 67 is also fed by the output of Delay unit Dn 69.

The output of AEC3 67 is fed to first speaker 31.

Delay unit Dn 69 compensates for network delays and is fed by Dnestimation module 68 (that estimates Dn) and by an output of AFC 71.

The output of first microphone 41 is fed to a sequence of threecompensation modules that includes AEC1 65, AEC2 66 and AFC 71.

The output of AFC 71 is also fed to Delay unit Dtx 64. Delay unit Dtx 64performs Dtx compensation and outputs a Dtx compensated signal to firstI/O port 51. Delay unit Dtx 64 is also fed by Dtx estimation module 63.Dtx estimation module 63 estimated Dtx.

FIG. 9B illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules of a first deviceof a first person according to an embodiment of the invention.

FIG. 9B differs from FIG. 9A by including a combined first and secondecho cancellation units AEC12 72 instead of the pair of serially coupledAEC1 61 and AEC2 66.

FIG. 9C illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules of a first deviceof a first person according to an embodiment of the invention.

FIG. 9C differs from FIG. 9B by not including AFC 71. The output ofcombined first and second echo cancellation units AEC12 72 is fed toDelay unit Dn 69 and Delay unit Dtx 64.

FIG. 9D illustrates various components (such as first microphone 41 andfirst speaker 31) and one or more compensation modules of a first deviceof a first person according to an embodiment of the invention.

FIG. 10A illustrates a third person that talks during conference call, anear end network, a connecting network, three devices and varioussignals generated during the conference call according to an embodimentof the invention.

FIG. 10B illustrates a person that talks during conference call, a nearend network, a connecting network, three devices and various signalsgenerated during the conference call according to an embodiment of theinvention.

FIG. 11A illustrates a third person 13 and a first person 11 that talkduring conference call, a mixer 25, three devices 21, 22 and 23 thatinclude a second device 22 that has a turned off microphone (OFF), andvarious signals 1011, 1031, 1032, 1111, 1131, 1132, 1310, 1330, 1410 and1430 generated during the conference call according to an embodiment ofthe invention.

FIG. 11B illustrates a third person 13 and a first person 11 that talkduring conference call, a mixer 25, three devices 21, 22 and 23 thatinclude a second device 22 that has a turned off speaker (OFF), andvarious signals 1011, 1012, 1031, 1111, 1112, 1131, 1132, 1310, 1330,1410 and 1430 generated during the conference call according to anembodiment of the invention.

FIG. 11C illustrates a third person and a first person that talk duringconference call, a mixer, three devices that include a second devicethat has a turned off (OFF) microphone and a first device with a turnedoff (OFF) speaker, and various signals 1011, 1012, 1032, 1111, 1131,1132, 1310, 1330, 1410 and 1430 generated during the conference callaccording to an embodiment of the invention.

FIG. 11D illustrates a third person and a first person that talk duringconference call, a mixer, three devices that include a second devicethat has a turned off (OFF) microphone, a third device with a turned off(OFF) microphone, and a first device with a turned off (OFF) speaker, aswell as various signals 1011, 1012, 1032, 1111, 1131, 1141, 1310, 1410and 1430 generated during the conference call according to an embodimentof the invention.

FIG. 12A illustrates a second person that talks during conference call,a mixer, three devices, and various signals 1330, 1601, 1602, 1603,1604, 1605, 1606, 1607 and 1608 generated during the conference callaccording to an embodiment of the invention.

Any reference to the term “comprising” or “having” should be interpretedalso as referring to “consisting” of “essentially consisting of”. Forexample—a method that comprises certain steps can include additionalsteps, can be limited to the certain steps or may include additionalsteps that do not materially affect the basic and novel characteristicsof the method—respectively.

The invention may also be implemented in a computer program for runningon a computer system, at least including code portions for performingsteps of a method according to the invention when run on a programmableapparatus, such as a computer system or enabling a programmableapparatus to perform functions of a device or system according to theinvention. The computer program may cause the storage system to allocatedisk drives to disk drive groups.

A computer program is a list of instructions such as a particularapplication program and/or an operating system. The computer program mayfor instance include one or more of: a subroutine, a function, aprocedure, an object method, an object implementation, an executableapplication, an applet, a servlet, a source code, an object code, ashared library/dynamic load library and/or other sequence ofinstructions designed for execution on a computer system.

The computer program may be stored internally on a non-transitorycomputer readable medium. All or some of the computer program may beprovided on computer readable media permanently, removably or remotelycoupled to an information processing system. The computer readable mediamay include, for example and without limitation, any number of thefollowing: magnetic storage media including disk and tape storage media;optical storage media such as compact disk media (e.g., CD-ROM, CD-R,etc.) and digital video disk storage media; nonvolatile memory storagemedia including semiconductor-based memory units such as FLASH memory,EEPROM, EPROM, ROM; ferromagnetic digital memories; MRAM; volatilestorage media including registers, buffers or caches, main memory, RAM,etc. A computer process typically includes an executing (running)program or portion of a program, current program values and stateinformation, and the resources used by the operating system to managethe execution of the process. An operating system (OS) is the softwarethat manages the sharing of the resources of a computer and providesprogrammers with an interface used to access those resources. Anoperating system processes system data and user input, and responds byallocating and managing tasks and internal system resources as a serviceto users and programs of the system. The computer system may forinstance include at least one processing unit, associated memory and anumber of input/output (I/O) devices. When executing the computerprogram, the computer system processes information according to thecomputer program and produces resultant output information via I/Odevices.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the broader spirit and scope of theinvention as set forth in the appended claims.

Moreover, the terms “front,” “back,” “top,” “bottom,” “over,” “under”and the like in the description and in the claims, if any, are used fordescriptive purposes and not necessarily for describing permanentrelative positions. It is understood that the terms so used areinterchangeable under appropriate circumstances such that theembodiments of the invention described herein are, for example, capableof operation in other orientations than those illustrated or otherwisedescribed herein.

Those skilled in the art will recognize that the boundaries betweenlogic blocks are merely illustrative and that alternative embodimentsmay merge logic blocks or circuit elements or impose an alternatedecomposition of functionality upon various logic blocks or circuitelements. Thus, it is to be understood that the architectures depictedherein are merely exemplary, and that in fact many other architecturesmay be implemented which achieve the same functionality.

Any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality may be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundariesbetween the above described operations merely illustrative. The multipleoperations may be combined into a single operation, a single operationmay be distributed in additional operations and operations may beexecuted at least partially overlapping in time. Moreover, alternativeembodiments may include multiple instances of a particular operation,and the order of operations may be altered in various other embodiments.

Also for example, in one embodiment, the illustrated examples may beimplemented as circuitry located on a single integrated circuit orwithin a same device. Alternatively, the examples may be implemented asany number of separate integrated circuits or separate devicesinterconnected with each other in a suitable manner.

Also for example, the examples, or portions thereof, may implemented assoft or code representations of physical circuitry or of logicalrepresentations convertible into physical circuitry, such as in ahardware description language of any appropriate type.

Also, the invention is not limited to physical devices or unitsimplemented in non-programmable hardware but can also be applied inprogrammable devices or units able to perform the desired devicefunctions by operating in accordance with suitable program code, such asmainframes, minicomputers, servers, workstations, personal computers,notepads, personal digital assistants, electronic games, automotive andother embedded systems, cell phones and various other wireless devices,commonly denoted in this application as ‘computer systems’.

However, other modifications, variations and alternatives are alsopossible. The specifications and drawings are, accordingly, to beregarded in an illustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps then those listed in aclaim. Furthermore, the terms “a” or “an,” as used herein, are definedas one or more than one. Also, the use of introductory phrases such as“at least one” and “one or more” in the claims should not be construedto imply that the introduction of another claim element by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim element to inventions containing only one suchelement, even when the same claim includes the introductory phrases “oneor more” or “at least one” and indefinite articles such as “a” or “an.”The same holds true for the use of definite articles. Unless statedotherwise, terms such as “first” and “second” are used to arbitrarilydistinguish between the elements such terms describe. Thus, these termsare not necessarily intended to indicate temporal or otherprioritization of such elements. The mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

We claim:
 1. A mobile communication device that comprises a microphone,a speaker, an input output port and one or more modules; wherein themicrophone is configured to receive, during a conference call, (a) anacoustic signal from a first user, and (b) a first user second devicecross echo that is an echo from another mobile communication thatparticipated in the conference call, the first user second device echoresults from a digital leakage signal from the other mobilecommunication device that passes through a mixer that does not belong tothe mobile communication device and is coupled between the mobilecommunication device and the other mobile communication device, thedigital leakage signal is generated by the other mobile communicationdevice in response to a reception of the acoustic signal from the firstuser; and wherein the one or more modules comprise: a delay unitconfigured to delay the first user second device cross echo by a delayto provide a delayed acoustic signal; and an echo cancellation unit thatis configured to receive the first user second device cross echo and thedelayed acoustic signal and to perform echo cancellation using acorrelation between the delayed acoustic signal and the first usersecond device cross echo.
 2. The mobile communication device accordingto claim 1 wherein the echo cancellation unit is configured to mute thespeaker.
 3. The mobile communication device according to claim 1 whereinthe input output port is configured to receive a first user first devicedigital leakage signal that is a digital leakage signal generated by theother communication device as a response to the acoustic signal from thefirst user, wherein the first user first device leakage signal passedthrough the mixer; and wherein the one or more modules are configured touse the first user first device digital leakage signal as a referencesignal during the echo cancellation.
 4. The mobile communication deviceaccording to claim 3 wherein the one or more modules comprises multipledelay units, multiple delay estimation modules and multiple echocancellation units.
 5. The mobile communication device according toclaim 4 wherein the multiple echo cancellation units comprise a sequenceof echo cancellation units and another echo cancellation unit that doesnot belong to the sequence.
 6. The mobile communication device accordingto claim 1, wherein the input output port is configured to receive, froma further mobile communication device, a digital signal that is relatedto acoustic signal generated by a further user.
 7. The mobilecommunication device according to claim 6 wherein the one or moremodules are configured to compensate for differences between delaysassociated with (a) a reception of traffic from the further mobilecommunication device by the mobile communication device and (b) areception of traffic from the further mobile communication device by theother mobile communication device.
 8. The mobile communication deviceaccording to claim 1 wherein the one or more modules are configured tochange a signal that is provided to the speaker.
 9. A mobilecommunication device that comprises a single microphone, a speaker, aninput output port and one or more modules; wherein the microphone isconfigured to receive, during a conference call, (a) an acoustic signalfrom a first user, and (b) an echo from a speaker of the mobilecommunication device, the echo is generated as a result of a digitalleakage signal from another mobile communication device thatparticipates in the conference call, the digital leakage signal passesthrough a mixer that does not belong to the mobile communication deviceand is coupled between the mobile communication device and the othermobile communication device, the digital leakage signal results from theacoustic signal of the first user; wherein the one or more modules areconfigured to cancel the echo based on the acoustic signal of the firstuser; wherein the mobile communication device does not include anymicrophones except the single microphone.
 10. The mobile communicationdevice according to claim 9 wherein the one or more modules areconfigured to change a signal that is fed to the speaker.
 11. The mobilecommunication device according to claim 9 wherein the one or moremodules are configured to cancel a signal that is fed to the speaker.12. A method for participating in a conference call, the method isexecuted by a mobile communication device that comprises a microphone, aspeaker, an input output port and one or more modules, wherein themethod comprises: receiving, by the microphone, during the conferencecall, (a) an acoustic signal from a first user, and (b) a first usersecond device cross echo that is an echo from another mobilecommunication that participated in the conference call, the first usersecond device echo results from a digital leakage signal from the othermobile communication device that passes through a mixer that does notbelong to the mobile communication device and is coupled between themobile communication device and the other mobile communication device,the digital leakage signal is generated by the other mobilecommunication device in response to a reception of the acoustic signalfrom the first user; and cancelling, by the one or more modules, thefirst user second device cross echo; wherein the cancelling comprises:delaying, by a delay unit, the first user second device cross echo by adelay to provide a delayed acoustic signal; and receiving by an echocancellation unit, the first user second device cross echo and thedelayed acoustic signal; and performing echo cancellation using acorrelation between the delayed acoustic signal and the first usersecond device cross echo.
 13. The method according to claim 12comprising muting the microphone by the echo cancellation unit.
 14. Themethod according to claim 13 comprising cancelling the cross echo by anecho cancellation unit and cancelling the digital leakage signal byanother echo cancellation unit.
 15. The method according to claim 12,comprising receiving by the input output port a first user first devicedigital leakage signal that is a digital leakage signal generated by theother communication device as a response to the acoustic signal from thefirst user, wherein the first user first device leakage signal passedthrough the mixer; and wherein the method comprises using the first userfirst device digital leakage signal as a reference signal during theecho cancellation.
 16. The method according to claim 15 wherein theperforming of the echo cancellation is executed by multiple delay units,multiple delay estimation modules, and multiple echo cancellation units.17. The method according to claim 16 wherein the multiple echocancellation units comprise a sequence of echo cancellation units andanother echo cancellation unit that does not belong to the sequence. 18.The method according to claim 12, comprising receiving, by the inputoutput port, from a further mobile communication device, a digitalsignal that is related to acoustic signal generated by a further user.19. The method according to claim 18 comprising compensating, by the oneor more modules, for differences between delays associated with (a) areception of traffic from the further mobile communication device by themobile communication device and (b) a reception of traffic from thefurther mobile communication device by the other mobile communicationdevice.
 20. The method according to claim 12 comprising changing, by theone or more modules a signal that is provided to the speaker.
 21. Amethod for participating in a conference call, the method is executed bya mobile communication device that comprises a microphone, a singlespeaker, an input output port and one or more modules, wherein themobile communication device does not include any microphones except thesingle microphone; wherein the method comprises: receiving, by themicrophone, during a conference call, (a) an acoustic signal from afirst user, and (b) an echo from a speaker of the mobile communicationdevice, the echo is generated as a result of a digital leakage signalfrom another mobile communication device that participates in theconference call, the digital leakage signal passes through a mixer thatdoes not belong to the mobile communication device and is coupledbetween the mobile communication device and the other mobilecommunication device, the digital leakage signal results from theacoustic signal of the first user; and cancelling, by the one or moremodules, the echo based, at least in part, on the acoustic signal of thefirst user.
 22. The method according to claim 21 comprising changing, bythe one or more modules a signal that is provided to the speaker. 23.The method according to claim 22 comprising cancelling, by the one ormore modules a signal that is provided to the speaker.